#include <vtkSmartPointer.h>
#include <vtkCell.h>
#include <vtkImageData.h>

static void GetCellCenter(vtkImageData* imageData, const unsigned int cellId, 
                          double center[3]);

int main(int, char *[])
{
  // Create an image data
  vtkSmartPointer<vtkImageData> imageData = vtkSmartPointer<vtkImageData>::New();
  
  // Specify the size of the image data
  imageData->SetDimensions(3,3,2); // This will cause 18 points and 4 cells
  imageData->SetSpacing(1.0, 1.0, 1.0);
  imageData->SetOrigin(0.0, 0.0, 0.0);
  
  std::cout << "Number of points: " << imageData->GetNumberOfPoints() << std::endl;
  std::cout << "Number of cells: " << imageData->GetNumberOfCells() << std::endl;

  double center[3] = {0,0,0};
  for(vtkIdType cellId = 0; cellId < imageData->GetNumberOfCells(); ++cellId)
    {
    GetCellCenter(imageData, cellId, center);
    
    std::cout << "Cell " << cellId << " center: " << center[0] << " " 
              << center[1] << " " << center[2] << std::endl;
    }
  
  return EXIT_SUCCESS;
}

void GetCellCenter(vtkImageData* imageData, const unsigned int cellId, double center[3])
{
  double pcoords[3] = {0,0,0};
  double *weights = new double [imageData->GetMaxCellSize()];
  vtkCell* cell = imageData->GetCell(cellId);
  int subId = cell->GetParametricCenter(pcoords);
  cell->EvaluateLocation(subId, pcoords, center, weights);
}
